At a Glance
Why Get Tested?
To evaluate your pituitary function, especially as it relates to fertility issues, gonadal failure, maturation concerns, or pituitary tumors
When to Get Tested?
When you are having difficulty getting pregnant or are having irregular menstrual periods; when your doctor thinks that you have symptoms of pituitary or hypothalamic disorders or symptoms of ovarian or testicular disease; or when a doctor suspects that a child has delayed or earlier than expected sexual maturation
Sample Required?
A blood sample drawn from a vein in your arm; sometimes a random urine sample or 24-hour urine collection may be taken
Test Preparation Needed?
None
The Test Sample
What is being tested?
Follicle-stimulating hormone (FSH) is made by the pituitary gland in the brain. Control of FSH production is a complex system involving hormones produced by the gonads (ovaries or testes), the pituitary, and the hypothalamus.
In women, FSH stimulates the growth and maturation of eggs (follicles) in the ovaries during the follicular phase of the menstrual cycle. The menstrual cycle is divided into the follicular and the luteal phases, characterized by a mid-cycle surge of FSH and luteinizing hormone (LH). Ovulation occurs shortly after this mid-cycle surge of hormones. During the follicular phase, FSH initiates the production of estradiol by the follicle, and the two hormones work together in the further development of the egg follicle. During the luteal phase, FSH stimulates the production of progesterone. Both estradiol and progesterone help the pituitary control the amount of FSH produced. FSH also facilitates the ability of the ovary to respond to LH. At the time of menopause, the ovaries stop functioning and FSH levels rise. In men, FSH stimulates the testes to produce mature sperm and also promotes the production of androgen binding proteins. FSH levels are relatively constant in males after puberty.
In infants and children, FSH levels rise shortly after birth and then fall to very low levels by 6 months in boys and 1-2 years in girls. Concentrations begin to rise again before the beginning of puberty and the development of secondary sexual characteristics.
How is the sample collected for testing?
A blood sample is drawn by needle from a vein in the arm. Sometimes, a random urine sample is collected but, due to the cyclic secretion of FSH, a 24-hour collection of urine may be requested. By measuring FSH levels produced over a 24-hour period, the variation in FSH levels seen through out the day can be minimized.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is required, but a woman's sample should be collected at specific times during her menstrual cycle.
The Test
How is it used?
FSH is often used in conjunction with other tests (LH, testosterone, estradiol, and progesterone) in the workup of infertility in both men and women. FSH levels are used to help determine the reason a man has a low sperm count. FSH levels are also useful in the investigation of menstrual irregularities and to aid in the diagnosis of pituitary disorders or diseases involving the ovaries or testes. In children, FSH and LH are used to diagnose delayed or precocious (early) puberty.
When is it ordered?
In women and men, FSH and LH are ordered as part of the workup of infertility and pituitary or gonadal disorders.
FSH may be ordered when a woman's menstrual cycle has stopped or become irregular, to determine if the woman has entered menopause.
In children, FSH and LH may be ordered when a boy or girl does not appear to be entering puberty at an appropriate age (either too late or too soon). Signs of early (precocious) puberty may include:
- Breast enlargement in females
- Growth of pubic hair
- Genitalia growth in males
- Beginning of menstruation in females
Irregular timing of puberty may be an indication of a more serious problem involving the hypothalamus, the pituitary gland, the gonads (ovaries or testes), or other systems. The measurement of LH and FSH may help differentiate between benign symptoms and true disease. Once it is established that symptoms are a result of true disease, further testing can be done to discern the underlying cause.
What does the test result mean?
In women, FSH and LH levels can help to differentiate between primary ovarian failure (failure of the ovaries themselves) and secondary ovarian failure (failure of the ovaries due to disorders of either the pituitary or the hypothalamus). Increased levels of FSH and LH are consistent with primary ovarian failure. Some causes of primary ovarian failure are listed below.
Developmental defects:
- Failure to develop ovaries (ovarian agenesis)
- Chromosomal abnormality, such as Turner's syndrome
- Defect in the steroid production by the ovaries, such as 17 alpha hydroxylase deficiency
Premature ovarian failure due to:
- Radiation
- Chemotherapy
- Autoimmune disease
Chronic failure to ovulate (anovulation) due to:
- Polycystic ovary syndrome (PCOS)
- Adrenal disease
- Thyroid disease
- Ovarian tumor
When a woman enters menopause and her ovaries stop working, FSH levels will rise.
Low levels of FSH and LH are consistent with secondary ovarian failure due to a pituitary or hypothalamic problem. Low FSH serum levels have been associated with increased risk of ovarian cancer.
In men, high FSH levels are due to primary testicular failure. This can be due to developmental defects in testicular growth or to testicular injury, as indicated below.
Developmental defects:
- Failure to develop gonads (gonadal agenesis)
- Chromosomal abnormality, such as Klinefelters syndrome
Testicular failure:
Low levels are consistent with pituitary or hypothalamic disorders.
High levels of FSH and LH with the development of secondary sexual characteristics at an unusually young age are an indication of precocious puberty. This is much more common in girls than in boys. This premature development can have many different underlying causes that need to be diagnosed and treated. Some of the causes include:
- Central nervous system lesions
- Hormone-secreting tumors
- Ovarian tumors or cysts
- Testicular tumors
Normal prepubescent levels of LH and FSH in children exhibiting some signs of pubertal changes may indicate a benign form of precocious puberty with no underlying or discernable cause or may just be a normal variation of puberty.
In delayed puberty, LH and FSH levels can be normal or below what is expected for a youth within this age range. A test for LH response to GnRH may need to be performed along with other testing to diagnose the reason for the delayed puberty. Some of the causes for delayed puberty can include:
- Gonadal (ovary or testes) failure
- Hormone deficiency
- Turner's syndrome (chromosomal abnormality in girls)
- Klinefelter's syndrome (chromosomal abnormality in boys)
- Chronic infections
- Cancer
- Eating disorder (anorexia nervosa)
Is there anything else I should know?
FSH results can be increased with use of cimetidine, clomiphene, digitalis, and levodopa. FSH results can decrease with oral contraceptives, phenothiazines, and hormone treatments. FSH has been reported to increase with age and in smokers.
A recent nuclear medicine scan may interfere with results of the FSH test.
Common Questions
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Related Pages
On This Site
Conditions: Infertility, Menopause, Pituitary disorders, Endocrine Syndromes, PCOS
Elsewhere On The Web
Article Sources
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 629-631.
Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 412-416.
Storck, S. (Updated 2009 September 2). FSH. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003710.htm. Accessed February 2010.
Jabbour, S. (Updated 2009 June 15). Follicle-Stimulating Hormone Abnormalities. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/118810-overview through http://emedicine.medscape.com. Accessed February 2010.
Meikle, A. W. et. al. (Updated 2009 November). Amenorrhea. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/Amenorrhea.html# through http://www.arupconsult.com. Accessed February 2010.
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MedlinePlus Health Topics: Female Reproductive System. Available online at http://www.nlm.nih.gov/medlineplus/femalereproductivesystem.html through http://www.nlm.nih.gov. Accessed February 2010.
Clarke, W. and Dufour, D. R., Editors (© 2006). Contemporary Practice in Clinical Chemistry: AACC Press, Washington, DC. Pp 360-361.
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Sources Used in Previous Reviews
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Clinical Guide to Laboratory Tests. 3rd ed. Tietz N, ed. Philadelphia: W.B. Saunders & Co; 1995: 248-249, 210-211.
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Laurence M. Demers, PhD. Distinguished Professor of Pathology and Medicine, The Pennsylvania State University College of Medicine, The M. S. Hershey Medical Center, Hershey, PA.
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